Apparatus and method for removal of oxide and carbon from semiconductor films in a single processing chamber

ABSTRACT

A system and method for removing both carbon-based contaminants and oxygen-based contaminants from a semiconductor substrate within a single process chamber is disclosed. The invention may comprise utilization of remote plasma units and multiple gas sources to perform the process within the single process chamber.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

The present disclosure claims the benefit of U.S. Provisional PatentApplication No. 62/532,248, filed on Jul. 13, 2017 and entitled“APPARATUS AND METHOD FOR REMOVAL OF OXIDE AND CARBON FROM SEMICONDUCTORFILMS IN A SINGLE PROCESSING CHAMBER,” which is incorporated herein byreference.

FIELD OF INVENTION

The present disclosure generally relates to an apparatus and a methodfor manufacturing electronic devices. More particularly, the disclosurerelates to removal of oxide and carbon within semiconductor films formedin a processing chamber.

BACKGROUND OF THE DISCLOSURE

Prior to the fabrication of semiconductor device, a clean surface of awafer or substrate is desired. Contaminates on the substrate mayadversely affect mechanical and electrical properties of thesemiconductor devices formed. It is desired that these contaminates beremoved before particular films are deposited onto the substrate.

Contaminants that exist on a silicon or silicon germanium substrate mayinclude carbon-based contaminants, such as carbonaceous contaminants andhydrocarbon contaminates. Other contaminants may include oxygen-basedcontaminants, such as native oxides, for example. It may be imperativeto remove these contaminants before epitaxial processes can take place.

Prior approaches to contaminant removal focus on removing one of thecontaminants, either carbon-based or oxygen-based, but not both. Thismay be in part due to equipment limitations of the prior approaches. Asa result, a system and method to remove both carbon-based andoxygen-based contaminants is desired.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

These and other features, aspects, and advantages of the inventiondisclosed herein are described below with reference to the drawings ofcertain embodiments, which are intended to illustrate and not to limitthe invention.

FIG. 1 is a cross-sectional illustration of a system in accordance withat least one embodiment of the invention.

FIG. 2 is a cross-sectional illustration of a system in accordance withat least one embodiment of the invention.

FIGS. 3A, 3B and 3C are flowcharts of methods in accordance with atleast one embodiment of the invention.

FIG. 4 is a flowchart of a step in accordance with at least oneembodiment of the invention.

FIG. 5 is a flowchart of a step in accordance with at least oneembodiment of the invention.

FIG. 6 is a flowchart of a step in accordance with at least oneembodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it willbe understood by those in the art that the invention extends beyond thespecifically disclosed embodiments and/or uses of the invention andobvious modifications and equivalents thereof. Thus, it is intended thatthe scope of the invention disclosed should not be limited by theparticular disclosed embodiments described below.

Embodiments of the invention are directed to a system with a singleprocess chamber having a capability to remove both carbon-basedcontaminants and oxygen-based contaminants. The embodiments have severaladvantages over prior approaches including: (1) incorporation of atleast one remote plasma unit (RPU) with the ability to generate bothhydrogen radicals and fluorine radicals; and (2) compatibility of theprocess chamber with both hydrogen radicals and fluorine radicals.

Embodiments of the invention may be used to clean semiconductorsubstrates made of at least one of the following materials: silicon;silicon germanium; or germanium, for example. In one embodiment, thepercentage of germanium in silicon germanium may vary from 10% to 90%.Also, embodiments of the invention may be used to etch carbon layers,such as an advanced patterning film (APF); photoresists; or other carboncontaminations including CHF_(x), SiC, or SiOC. In addition, embodimentsof the invention may be used to clean a surface of dielectric materials,such as silicon oxide, silicon nitride, silicon oxynitride, fluorinatedsilicon oxide, silicon carboxide, and silicon carboxynitride.Furthermore, embodiments of the invention may be applied to patternedwafer surfaces.

FIG. 1 illustrates a system 100 in accordance with at least oneembodiment of the invention. The system 100 may comprise a reactionchamber 110, a susceptor 120, a showerhead 130, a remote plasma unit140, and a transport path 145 between the remote plasma unit 140 and thereaction chamber 110. A substrate 150 is placed on the susceptor 120 forprocessing.

The reaction chamber 110 defines a space in which the substrate 150 isprocessed. The reaction chamber 110, the susceptor 120, the showerhead130, and the transport path 145 may be coated with materials or bulkceramic material in order to allow for compatibility with differentradicals. The materials for coating may include at least one of:anodized aluminum oxide (Al₂O₃); atomic layer deposition (ALD)-formedaluminum oxide; plasma sprayed Al₂O₃; bare aluminum parts with nativealuminum oxide, yttrium oxide (Y₂O₃); yttrium oxide stabilized zirconiumoxide (YSZ); zirconium oxide (ZrO₂); lanthanum zirconium oxide (LZO);yttrium aluminum garnet (YAG); yttrium oxyfluoride (YOF); combination ofthe above materials; or the above substrate doped with other glass phasematerials. In some cases, the coating materials can be made with twolayers. For example, the first layer may be coated with anodized Al₂O₃and the second layer may be coated with ALD-formed Al₂O₃. The coatingmay be amorphous phase, crystalline phase, or mixed. The bulk ceramicmaterial may include: aluminum oxide (Al₂O₃); zirconium oxide (ZrO₂);yttrium oxide (Y₂O₃); or yttrium oxide stabilized zirconium oxide (YSZ).

The system 100 also may comprise a first gas source 160, a second gassource 170, a third gas source 180, and a fourth gas source 190, whichall may provide gas to the remote plasma unit 140. The remote plasmaunit 140 may comprise a Paragon H* remote plasma unit from MKSInstruments, for example. The third gas source 180 may also beconfigured to provide gas directly into the reaction chamber 110 withoutgoing through the remote plasma unit 140. The first gas source 160 maycomprise a source of a precursor gas that produces fluorine radicals,such as NF₃, CF₄, C₂F₆, C₄F₆, C₄F₈, COF₂, SF₆, or WF₆, for example. Thesecond gas source 170 may comprise a source of a gas that produceshydrogen radicals, such as H₂, NH₃, or H₂O, for example. The second gassource 170 may comprise a gas that produces oxygen radicals, such asoxygen or ozone, for example. The third gas source 180 may be a sourceof NH₃. The fourth gas source 190 may be a source of an inert gas, suchas argon, helium, nitrogen, or neon, for example.

The remote plasma unit 140 generates radicals provided from the gassources. The generated radicals then enter the reaction chamber 110through the showerhead 130 and then flow onto the substrate 150. Theremote plasma source may include: a toroidal style ICP source or a coilstyle ICP source driven by different RF frequencies, such as a 400 kHz,2 MHz, 60 MHz and 2.56 GHz microwave source.

FIG. 2 illustrates a system 200 in accordance with at least oneembodiment of the invention. The system 200 may comprise a reactionchamber 210, a susceptor 220, a showerhead 230, a first remote plasmaunit 240 dedicating for oxide removal with F*, a second remote plasmaunit 245 dedicating for carbon removal with H*, a transport path 246below the first remote plasma unit, and a transport path 247 below thesecond remote plasma unit. A substrate 250 is placed on the susceptor220 for processing. The system 200 may also comprise a first gate vale248 and a second gate valve 249.

The reaction chamber 210 defines a space in which the substrate 250 isprocessed. The reaction chamber 210, the susceptor 220, and theshowerhead 230 may be coated with materials or bulk ceramic material inorder to allow for compatibility with different radicals, such as:anodized aluminum oxide (Al₂O₃); atomic layer deposition (ALD)-formedaluminum oxide; plasma sprayed Al₂O₃; bare aluminum parts with nativealuminum oxide; yttrium oxide (Y₂O₃); yttrium oxide stabilized zirconiumoxide (YSZ); zirconium oxide (ZrO₂); lanthanum zirconium oxide (LZO);yttrium aluminum garnet (YAG); yttrium oxyfluoride (YOF); combination ofthe above materials; or the above substrate doped with other glass phasematerials. In some cases, the coating materials may be made with twolayers. For example, the first layer may be coated with anodized Al₂O₃and the second layer may be coated with ALD-formed Al₂O₃. The coatingmay be amorphous phase, crystalline phase, or mixed. The bulk ceramicmaterial may include: aluminum oxide (Al₂O₃); zirconium oxide (ZrO₂);yttrium oxide (Y₂O₃); or yttrium oxide-stabilized zirconium oxide (YSZ).Besides the above coatings and bulk materials for different radicals,materials for the transport path 247 below the second remote plasma unitmay also comprise bulk quartz material.

The system 200 also may comprise a first gas source 260, a second gassource 270, a third gas source 280, and a fourth gas source 290, whichall may provide gas to the first remote plasma unit 240 and the secondremote plasma unit 245. The first remote plasma unit 240 and the secondremote plasma unit 245 may comprise a toroidal style ICP source or acoil style ICP source driven by different RF frequencies, such as a 400kHz, 2 MHz, 60 MHz and 2.56 GHz microwave source, for example. The thirdgas source 280 may also be configured to provide gas directly into thereaction chamber 210 without going through the first remote plasma unit240 or the second remote plasma unit 245. The first gas source 260 maycomprise a source of a precursor gas that produces fluorine radicals,such as NF₃, CF₄, C₂F₆, C₄F₆, C₄F₈, COF₂, SF₆, or WF₆, for example. Thesecond gas source 270 may comprise a source of gas that produceshydrogen radicals, such as H₂, NH₃, or H₂O, for example. The second gassource 270 may comprise a gas that produces oxygen radicals, such asoxygen or ozone, for example. The third gas source 280 may be a sourceof NH₃. The fourth gas source 290 may be a source of an inert gas, suchas argon, helium, nitrogen, or neon, for example.

The first remote plasma unit 240 (which may be dedicated for F*radicals) and the second remote plasma unit 245 (which may be dedicatedfor H* radicals) generate radicals provided from the gas sources. Thegenerated radicals then enter the reaction chamber 210 through theshowerhead 230 and then flow onto the substrate 250. To prevent radicalsgenerated by one remote plasma unit back streaming into the secondremote plasma, the gate valves 248 and 249 may be located at the outletof RPU.

FIG. 3A illustrates a method in accordance with at least one embodimentof the invention. The method comprises an oxide conversion step 300, anoxide sublimation step 400, and a carbon removal step 500. Any of thesesteps or any combination of these steps may be repeated as needed. Theentire method may be repeated through a repeat cycle 600.

FIG. 3B illustrates a method in accordance with at least one embodimentof the invention. The method comprises a carbon removal step 500, anoxide conversion step 300, and an oxide sublimation step 400. Any ofthese steps or any combination of these steps may be repeated as needed.The entire method may be repeated through a repeat cycle 600. The methodof FIG. 3B differs from that of FIG. 3A in that the carbon removal step500 comes before the oxide conversion step 300.

FIG. 3C illustrates a method in accordance with at least one embodimentof the invention. The method comprises a carbon removal step 500, anoxide conversion step 300, an oxide sublimation step 400, and a carbonremoval step 500. Any of these steps or any combination of these stepsmay be repeated as needed. The entire method may be repeated through arepeat cycle 600. The method of FIG. 3C differs from that of FIG. 3B inthat an additional carbon removal step 500 comes after the oxidesublimation step 400.

In accordance with at least one embodiment of the invention, the oxideconversion step 300 is illustrated in FIG. 4. The oxide conversion step300 may comprises a step 310 of flowing gaseous precursors into a remoteplasma unit and a step 320 of flowing generated radicals and anadditional precursor onto a substrate. In accordance with at least oneembodiment of the invention, the step 310 may comprise flow of argon,hydrogen, and NF₃ into the remote plasma unit. A flow of argon may rangebetween 0.01 and 20 slm, between 0.1 and 10 slm, or between 1 and 8 slm.A flow of hydrogen may range between 10 sccm and 1500 slm, between 25and 1200 slm, or between 50 sccm and 1000 slm. A flow of NF₃ may occurfor a particular amount of time while the plasma is on in the remoteplasma unit, ranging between 0.1 and 120 seconds, between 1 and 100seconds, or between 5 and 80 seconds. The step 310 may comprise heatingthe reaction chamber 210 to a temperature between than 5 to 120° C.,between than 5 to 80° C., or between than 5 to 60° C.

As a result of step 310, a gas of fluorine radicals is generated in theremote plasma unit. The fluorine radicals leave the remote plasma unitand may combine with an optional additional precursor gas in step 320onto the substrate disposed in a reaction chamber. The optionaladditional precursor gas may comprise ammonia flowed at a rate rangingbetween 10 sccm and 1500 slm, between 25 and 1200 slm, or between 50sccm and 1000 slm. The step 320 may comprise heating the reactionchamber 210 to a temperature between than 5 to 120 ° C., between than 5to 80° C., or between than 5 to 60° C. The oxide conversion step 300 mayresult in a chemical reaction with oxides on a silicon germaniumsubstrate having an oxide as follows:

NH₄F_((g))+SiGeO_(x(s))→(NH₄)₂SiF_(6(s))+(NH₄)₂GeF_(6(s))+H₂O_((g))

As a result of the oxide conversion step 300, the oxide may be convertedinto a solid ammonium-hexafluorosilicate compound and a solidammonium-hexafluorogermanate compound on the substrate.

In accordance with at least one embodiment of the invention, the oxidesublimation step 400 is illustrated in FIG. 5. The oxide sublimationstep 400 comprises a first heating step 410, or a second heating step420, or both. The first heating step 410 may comprise heating thesubstrate to a temperature greater than 125° C., greater than 100° C.,or greater than 90° C. The result of the first step 410 may besublimation of the solid ammonium-hexafluorosilicate compound accordingto the following reaction:

(NH₄)₂SiF_(6(s))→NH_(3(g))+HF_((g))+SiF_(4(g))

The gaseous products may then be removed from the reaction chamber.

The second heating step 420 may comprise heating the substrate to ahigher temperature than that of the first heating step 410. Thetemperature may be greater than 275° C., greater than 250° C., orgreater than 225° C. To reach the high operation temperature, a hightemperature showerhead may be designed to heat up to 250° C.-300° C.without heating up the reaction chamber. The result of the second step420 may be sublimation of the solid ammonium-hexafluorogermanatecompound according to the following reaction:

(NH₄)₂GeF_(6(s))→NH_(3(g))+HF_((g))+GeF_(4(g))

The gaseous products may then be removed from the reaction chamber.

In accordance with at least one embodiment of the invention, the carbonremoval step 500 is illustrated in FIG. 6. The carbon removal step 500comprises a step 510 of flowing hydrogen precursors and other gaseousprecursors into a remote plasma unit and a step 520 of flowing generatedradicals and an optional additional precursor onto a substrate. Thefirst heating step 510 may comprise flowing argon, hydrogen, and ammoniainto the remote plasma unit. The gases may be flowed for a durationranging between 0.1 and 180 seconds, between 1 and 120 seconds, orbetween 10 and 90 seconds. As a result, hydrogen radicals are generatedin the remote plasma unit.

The step 520 takes the generated hydrogen radicals to react withcarbon-based contaminants in the substrate. This step may happen attemperatures between 25° C. and 500° C., between 75° C. and 400° C., orbetween 150° C. and 300° C. A higher temperature showerhead may allow toheat up substrate and leading to effective removal of carbon. The resultof the step 520 may be removal of the carbon according to the followingreaction:

C_((s))+H*_((g))→C_(x)H_(y(g))

Other reactions may include carbon with oxygen radicals. The gaseousproducts may then be removed from the reaction chamber.

The particular implementations shown and described are illustrative ofthe invention and its best mode and are not intended to otherwise limitthe scope of the aspects and implementations in any way. Indeed, for thesake of brevity, conventional manufacturing, connection, preparation,and other functional aspects of the system may not be described indetail. Furthermore, the connecting lines shown in the various figuresare intended to represent exemplary functional relationships and/orphysical couplings between the various elements. Many alternative oradditional functional relationship or physical connections may bepresent in the practical system, and/or may be absent in someembodiments.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. Thus, the various acts illustrated may beperformed in the sequence illustrated, in other sequences, or omitted insome cases.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,systems, and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

What is claimed is:
 1. An apparatus for processing a semiconductorsubstrate comprising: a reaction chamber; a susceptor configured to holda substrate; a first gas source for providing a first gas; a second gassource for providing a second gas; a first remote plasma unit configuredto receive the first gas and produce a first radical gas; a gasdistribution device configured to flow the first radical gas and thesecond gas onto the substrate; and a transport path connecting theremote plasma unit to the gas distribution device, wherein the firstradical gas passes through the gas distribution device onto thesubstrate; wherein the gas distribution device, the reaction chamber,the transport path, and the susceptor are coated with at least one of:anodized aluminum oxide (Al₂O₃); atomic layer deposition (ALD)-formedaluminum oxide; plasma sprayed Al₂O₃; bare aluminum parts with nativealuminum oxide; yttrium oxide (Y₂O₃); yttrium oxide stabilized zirconiumoxide (YSZ); zirconium oxide (ZrO₂); lanthanum zirconium oxide (LZO);yttrium aluminum garnet (YAG); yttrium oxyfluoride (YOF); aluminum oxide(Al₂O₃); zirconium oxide (ZrO₂); yttrium oxide (Y₂O₃); or yttrium oxidestabilized zirconium oxide (YSZ).
 2. The apparatus of claim 1, whereinthe first gas comprises at least one of: NF₃, CF₄, C₂F₆, C₄F₆, C₄F₈,COF₂, SF₆, or WF₆.
 3. The apparatus of claim 1, wherein the second gascomprises at least one of: H₂, NH₃, H₂O, O₂, or O₃.
 4. The apparatus ofclaim 1, further comprising: a third gas source for providing a thirdgas; and a fourth gas source for providing a fourth gas.
 5. Theapparatus of claim 4, wherein the third gas comprises NH₃.
 6. Theapparatus of claim 4, wherein the fourth gas comprises at least one of:argon, helium, nitrogen, or neon.
 7. The apparatus of claim 1, whereinthe first gas is used to remove an oxide from the substrate.
 8. Theapparatus of claim 1, wherein the second gas is used to remove carbonfrom the substrate.
 9. The apparatus of claim 1, wherein the second gaspasses through the first remote plasma unit and converts into a secondradical gas.
 10. The apparatus of claim 1, further comprising a secondremote plasma unit configured to receive the second gas and produce asecond radical gas.
 11. The apparatus of claim 1, wherein the transportpath comprises bulk quartz material.
 12. A method for processing asemiconductor substrate comprising: providing a reaction chamber and asusceptor configured to hold a substrate; performing an oxide conversionstep on the substrate, the oxide conversion step comprising: (1) flowinga first gas into a first remote plasma unit to form a first radical gas;and (2) flowing the first radical gas onto the substrate; performing anoxide sublimation step on the substrate, the oxide sublimation stepcomprising: (1) a first heating step; and (2) a second heating step; andperforming a carbon removal step on the substrate; wherein the oxideconversion step, the oxide sublimation step, and the carbon removal stepare each performed in the reaction chamber; and wherein any of the oxideconversion step, the oxide sublimation step, and the carbon removal stepare repeated as needed.
 13. The method of claim 12, wherein the carbonremoval step comprises: flowing a second gas into the first remoteplasma unit to form a second radical gas; and flowing the second radicalgas onto the substrate.
 14. The method of claim 12, wherein the carbonremoval step comprises: flowing a second gas into a second remote plasmaunit to form a second radical gas; and flowing the second radical gasonto the substrate.
 15. The method of claim 12, wherein the first gascomprises at least one of: NF₃, CF₄, C₂F₆, C₄F₆, C₄F₈, COF₂, SF₆, orWF₆.
 16. The method of claim 13, wherein the second gas comprises atleast one of: H₂, NH₃, H₂O, O₂, or O₃.
 17. A method for processing asemiconductor substrate comprising: providing a reaction chamber and asusceptor configured to hold a substrate; performing a carbon removalstep on the substrate; performing an oxide conversion step on thesubstrate, the oxide conversion step comprising: (1) flowing a first gasinto a first remote plasma unit to form a first radical gas; and (2)flowing the first radical gas onto the substrate; performing an oxidesublimation step on the substrate, the oxide sublimation stepcomprising: (1) a first heating step; and (2) a second heating step; andwherein the carbon removal step, the oxide conversion step, and theoxide sublimation step are each performed in the reaction chamber; andwherein any of the carbon removal step, the oxide conversion step, andthe oxide sublimation step are repeated as needed.
 18. The method ofclaim 17, wherein the carbon removal step comprises: flowing a secondgas into the first remote plasma unit to form a second radical gas; andflowing the second radical gas onto the substrate.
 19. The method ofclaim 17, wherein the carbon removal step comprises: flowing a secondgas into a second remote plasma unit to form a second radical gas; andflowing the second radical gas onto the substrate.
 20. The method ofclaim 17, wherein the first gas comprises at least one of: NF₃, CF₄,C₂F₆, C₄F₆, C₄F₈, COF₂, SF₆, or WF₆.
 21. The method of claim 18, whereinthe second gas comprises at least one of: H₂, NH₃, H₂O, O₂, or O₃.